// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "content/browser/browser_url_handler_impl.h"

#include <stddef.h>

#include "base/macros.h"
#include "base/strings/string_util.h"
#include "content/browser/frame_host/debug_urls.h"
#include "content/browser/webui/web_ui_impl.h"
#include "content/public/browser/content_browser_client.h"
#include "content/public/common/url_constants.h"
#include "url/gurl.h"

namespace content {

// Handles rewriting view-source URLs for what we'll actually load.
static bool HandleViewSource(GURL* url, BrowserContext* browser_context)
{
    if (url->SchemeIs(kViewSourceScheme)) {
        // Load the inner URL instead.
        *url = GURL(url->GetContent());

        // Bug 26129: limit view-source to view the content and not any
        // other kind of 'active' url scheme like 'javascript' or 'data'.
        static const char* const default_allowed_sub_schemes[] = {
            url::kHttpScheme,
            url::kHttpsScheme,
            url::kFtpScheme,
            kChromeDevToolsScheme,
            kChromeUIScheme,
            url::kFileScheme,
            url::kFileSystemScheme
        };

        // Merge all the schemes for which view-source is allowed by default, with
        // the WebUI schemes defined by the ContentBrowserClient.
        std::vector<std::string> all_allowed_sub_schemes;
        for (size_t i = 0; i < arraysize(default_allowed_sub_schemes); ++i)
            all_allowed_sub_schemes.push_back(default_allowed_sub_schemes[i]);
        GetContentClient()->browser()->GetAdditionalWebUISchemes(
            &all_allowed_sub_schemes);

        bool is_sub_scheme_allowed = false;
        for (size_t i = 0; i < all_allowed_sub_schemes.size(); ++i) {
            if (url->SchemeIs(all_allowed_sub_schemes[i].c_str())) {
                is_sub_scheme_allowed = true;
                break;
            }
        }

        if (!is_sub_scheme_allowed) {
            *url = GURL(url::kAboutBlankURL);
            return false;
        }

        return true;
    }
    return false;
}

// Turns a non view-source URL into the corresponding view-source URL.
static bool ReverseViewSource(GURL* url, BrowserContext* browser_context)
{
    // No action necessary if the URL is already view-source:
    if (url->SchemeIs(kViewSourceScheme))
        return false;
    // Recreate the url with the view-source scheme.
    *url = GURL(kViewSourceScheme + std::string(":") + url->spec());
    return true;
}

static bool DebugURLHandler(GURL* url, BrowserContext* browser_context)
{
    // Circumvent processing URLs that the renderer process will handle.
    return IsRendererDebugURL(*url);
}

// static
BrowserURLHandler* BrowserURLHandler::GetInstance()
{
    return BrowserURLHandlerImpl::GetInstance();
}

// static
BrowserURLHandler::URLHandler BrowserURLHandler::null_handler()
{
    // Required for VS2010: http://connect.microsoft.com/VisualStudio/feedback/details/520043/error-converting-from-null-to-a-pointer-type-in-std-pair
    return NULL;
}

// static
BrowserURLHandlerImpl* BrowserURLHandlerImpl::GetInstance()
{
    return base::Singleton<BrowserURLHandlerImpl>::get();
}

BrowserURLHandlerImpl::BrowserURLHandlerImpl()
    : fixup_handler_(nullptr)
{
    AddHandlerPair(&DebugURLHandler, BrowserURLHandlerImpl::null_handler());

    GetContentClient()->browser()->BrowserURLHandlerCreated(this);

    // view-source:
    AddHandlerPair(&HandleViewSource, &ReverseViewSource);
}

BrowserURLHandlerImpl::~BrowserURLHandlerImpl()
{
}

void BrowserURLHandlerImpl::SetFixupHandler(URLHandler handler)
{
    DCHECK(fixup_handler_ == nullptr);
    fixup_handler_ = handler;
}

void BrowserURLHandlerImpl::AddHandlerPair(URLHandler handler,
    URLHandler reverse_handler)
{
    url_handlers_.push_back(HandlerPair(handler, reverse_handler));
}

void BrowserURLHandlerImpl::RewriteURLIfNecessary(
    GURL* url,
    BrowserContext* browser_context,
    bool* reverse_on_redirect)
{
    for (size_t i = 0; i < url_handlers_.size(); ++i) {
        URLHandler handler = *url_handlers_[i].first;
        if (handler && handler(url, browser_context)) {
            *reverse_on_redirect = (url_handlers_[i].second != NULL);
            return;
        }
    }
}

void BrowserURLHandlerImpl::FixupURLBeforeRewrite(
    GURL* url,
    BrowserContext* browser_context)
{
    if (fixup_handler_)
        fixup_handler_(url, browser_context);
}

bool BrowserURLHandlerImpl::ReverseURLRewrite(
    GURL* url, const GURL& original, BrowserContext* browser_context)
{
    for (size_t i = 0; i < url_handlers_.size(); ++i) {
        URLHandler reverse_rewriter = *url_handlers_[i].second;
        if (reverse_rewriter) {
            GURL test_url(original);
            URLHandler handler = *url_handlers_[i].first;
            if (!handler) {
                if (reverse_rewriter(url, browser_context))
                    return true;
            } else if (handler(&test_url, browser_context)) {
                return reverse_rewriter(url, browser_context);
            }
        }
    }
    return false;
}

} // namespace content
